The invention relates to a height-adjustable bed, in particular a sickbed or nursing bed, and further to a length-adjustable supporting element which can be used as a supporting leg for a bed.
Height-adjustable sickbeds and/or nursing beds are e. g. known from DE-C-39 40 666 and DE-A-44 05 509. Both known beds are provided with a lifting lower frame comprising four supporting legs Interconnected by connecting beams. Each supporting leg comprises at its lower end a swivelling and/or guide roller. In the completely retracted position of the lower frame said rollers are free such that the bed can be moved. If, however, the lower frame is extended, the lower ends of the supporting leges are placed on the floor in the case of the bed according to DE-C-39 40 666, whereas the swivelling rollers are braked in the case of the bed according to DE-A-44 05 509. Both known beds are not movable when the lower frame is moved out of its lowermost lifted position.
To enhance the comfort provided by a sickbed and/or nursing bed it is sometimes required that the bed can, on the one hand, be lowered to a relatively low position such that the patient can easily rise from the bed or sit down on the bed. On the other hand, it is required that the bed can be lifted as high as possible such that it is easily positionable into a working height convenient for the nursing personnel. The supporting legs of the known nursing beds cannot be retracted and extended to a sufficient degree to fully meet these requirements.
It is an object of the invention to provide a bed, in particular a sickbed and/or nursing bed, as well as a length-adjustable supporting element usable as a supporting leg for such a bed, which has a small overall height and can be extended and retracted to a relatively large degree.
For solving this object the invention proposes a length-adjustable supporting element to be used as a supporting leg for a height-adjustable bed, in particular a sickbed and/or nursing bed, provided with a supporting leg,
a supporting leg comprising a supporting edge at its lower end,
a swivelling and/or guide roller comprising a tread and being received by said supporting leg, wherein the roller designed for moving purposes is displaceable from the lower end of the supporting leg beyond Its supporting edge and into the lower end of the supporting leg, and
a lifting means movable out of the upper end of the supporting leg and into the upper end of the supporting leg, said lifting means comprising a supporting member which is attachable to a first element of an object to be supported by the supporting leg.
For said supporting element it is, provided according to the invention
that the lifting means comprises a double-spindle arrangement having an inner spindle and a hollow spindle receiving said inner spindle,
that said double-spindle arrangement can be brought in engagement with a driving element to be driven by a driving device attachable to the supporting member or the first part of the object,
that the inner spindle threadedly engages with the hollow spindle and the hollow spindle threadedly engages with the supporting leg, and that the double-spindle arrangement cooperates with the retainiing element of the roller such that
in the maximum lifted position of both spindles relative to the supporting edge of the supporting leg, the tread of the roller is moved into the supporting leg or aligned with the supporting edge of the supporting leg,
in a minimum lifted position of both spindles, the tread of the roller is in alignment with the supporting edge of the supporting leg, and
in a minimum retracted position of both spindles, the tread of the roller protrudes from the supporting edge of the supporting leg, in which minimum retracted position said spindles are moved beyond the minimum lifted position further into the supporting leg than in their minimum lifted position.
In the supporting element according to the invention the lifting means is configured as a double-spindle arrangement comprising two spindles which can be axially telescoped and threadedly engage with each other. The inner spindle can be rotatably driven by a driving device. Thus the inner spindle rotatingly moves into the second spindle configured as a hollow spindle or out of said second spindle. The hollow spindle threadedly engages with the supporting leg. The double-spindle arrangement and the retaining element for the roller are disposed such that, in a maximum lifted position of the double-spindle arrangement relative to the supporting edge of the supporting leg, the tread of the roller is moved into the supporting leg or aligned with the supporting edge of the supporting leg. In a minimum lifted position of the double-spindle arrangement the tread of the roller is in alignment with the supporting edge of the supporting leg; in other words, the roller does not protrude downwards beyond the supporting edge of the supporting leg. If the double-spindle arrangement is moved into the supporting leg from the direction of the maximum lifted position via the minimum lifted position further up to a minimum retracted, position, the tread of the roller protrudes beyond the supporting edge of the supporting leg.
The mechanism according to the invention can, on the one hand, be realized by the retainer of the swivelling roller being fastened to the hollow spindle or the inner spindle thus moving, together with the spindle, through the supporting leg as a function of the respective lifted position of the double-spindle arrangement. An alternative to this concept is supporting the retainer to the lower end of the swivelling roller such that the retainer is movable in axial direction of the supporting leg without the retaining element being permanently connected with the double-spindle arrangement. If the two spindles are arranged in a telescopic tube having at least two tube sections, it is also possible that one or both tube sections contact the retaining element of the swivelling roller when the minimum retracted position is approached and ensure extension of the retaining element beyond the lower end of the supporting leg. When the two spindles move, by rotation about their axes, into the supporting leg, one of the two inner ends of the spindles contacts the retaining element of the roller. At the moment of contact of the spindles or at least one spindle with the retaining element the supporting leg is retracted, its upper end displaying a distance to the fastening element arranged at the upper end of the inner spindle. Upon further rotation of the spindles the supporting leg is moved towards the fastening element which results in the supporting edge of the supporting leg moving upwards such that the roller protrudes downwards beyond the supporting edge. Thus the object resting on the supporting element can be moved.
Thus the invention provides a supporting element which has a small overall height and can be extended up to a maximum lifted position, wherein the functions of automatically fixing the object supported by the supporting element to protect it against movements, and automatically releasing said object from said fixed state for the purpose of moving the object are further integrated.
In a preferred aspect of the invention it is provided that the double-spindle arrangement is covered when it is moved upwards out of the supporting leg. For this purpose the lifting device comprises at least one tube section telescoping with the supporting leg, the tube section being attached to the fastening element and coaxially enclosing the double-spindle arrangement. Said at least one tube section is guided along the supporting leg. Appropriately, two or more such tube sections, which can be telescoped, are employed, wherein the lowermost tube section facing the supporting leg is guided along the supporting leg and can be telescoped with the latter.
If it is intended that the supporting element according to the invention has a minimum axial length in its minimum lifted position, it is appropriate to provide at least two tube sections which can be telescoped with each other and with the supporting leg and cover the double-spindle arrangement. To allow the tube sections to move as deeply as possible into the supporting leg and the supporting element to display a minimum overall height, it is advantageous if the swivelling roller is arranged in a truncated insertion part which is inserted into the lower end of a tube forming the supporting leg. The peripheral area of said insertion part extends at an acute angle to the wall of the supporting leg tube such that the tube section/sections can be inserted in the minimum lifted position or the minimum retracted position of the double-spindle arrangement into the space, tapering towards the end of the supporting leg tube, between the insertion part and the supporting leg tube. The end of said insertion part arranged at the lower end of the supporting leg forms the supporting edge of the supporting element and is required to retain and support an inner tube arranged coaxially to the supporting leg tube, said inner tube threadedly engaging with the hollow spindle. The swivelling roller being permanently connected with the hollow spindle or the inner spindle, can now be displaced through an opening into the upper end of the insertion part averting the lower end of the supporting leg when the lifting position of the double-spindle arrangement changes. For reasons of stability it is however preferred that the retaining element of the swivelling roller is supported in the upper end of the truncated insertion part such that is can be axially displaced, so that the double-spindle arrangement cooperates in the aforementioned manner with the retaining element for the purpose of displacing said retaining element to move the swivelling roller out of the lower end of the supporting leg. In a preferred aspect of the invention a guide pulley is arranged at the upper end of the inner spindle, around which guide pulley an endless driving means in the form of a chain or a toothed or V-belt is guided. Such a belt drive is driven by the driving device and can, at the same time, drive one or a plurality of guide pulleys and thus inner spindles. For example, in the case of a bed the head-side and base-side pairs can each be driven, separately from supporting legs, by a respective belt drive alternatively, the double-spindle arrangements of all four supporting legs can be driven by a common belt drive. Appropriately, a belt drive configured as a toothed belt with gears meshing therewith and acting as the guide pulleys is used.
The extension and retracting movements of the two spindles out of the supporting leg and into the supporting leg are appropriately controlled or stopped by limit switches. In a preferred aspect the supporting element according to invention thus comprises a first limit switch, with one of two switching states of said limit switch signalling that the maximum lifting position has been reached. In the case of a double-section covering telescopic tube this maximum lifted position can be determined by inquiring the relative axial position of the two tube sections of the telescope. However, in the supporting element according to, the invention a three-section covering telescopic tube is used because of the requirement for as small an overall height as possible in the minimum lifted position, the supporting leg tube forming one of the three telescopic tube sections. Unfortunately, such a three-section telescopic tube does not allow to inquire that tube section which is, in this case, located nearest to the supporting leg tube about its position relative to the supporting leg tube to deduce the maximum lifted position. The reason for this is that the movement of the middle tube section during extension and retracting of the double-spindle arrangement is not defined.
In the preferred aspect of the invention to be described here a different principle is therefore applied for actuating the first limit switch. A first actuating element actuating the first limit switch is supported, such that it is movable between a first position and a second position, on the supporting member supporting the object to be supported. Said first actuating element is biased by a biasing force into the first position. Connected with the first actuating element is a pull element whose other end is fastened to an anchoring element which, in turn, is stationarily arranged relative to the supporting leg. Appropriately, said anchoring element is fastened to the supporting leg tube or, if present, to the inner tube arranged coaxially to the supporting leg tube and receiving the double-spindle arrangement. The anchoring element is located in the space between the inner tube and the supporting leg tube. When the double-spindle arrangement is extended und moved up to its maximum lifted position, the pull element exerts a pull force upon the actuating element when the maximum lifted position has been reached, which actuating element is thus moved from its first position, against the biasing force, into its second position. In this co nnection the switching state of the first limit switch is changed such that an electrical indication shows that the maximum lifted position has been reached.
The pull element may, e. g. be a traction rope, a chain or the like which is automatically wound up and thus shortened when the double-spindle arrangement is retracted into the supporting leg. For this purpose a take-up device is necessary. This requires relatively large efforts to be made. Therefore it would be better to configure the pull element as a telescopic rod with an inner rod and an outer rod axially guiding said inner rod, wherein one of the two rods is connected with the first actuating element and the other one is connected with the anchoring element. The telescopic rod is extended by pulling the inner rod out of the outer rod until it has reached its maximum length. Due to its permanent anchoring to the; anchoring element the pull rod acts upon the first actuating element when the maximum lifted position has been reached to move said actuating element relative to the supporting member and against the biasing force into the second position. Owing to the telescopic rod arrangement the pull element can be telescoped to a relatively short dimension, which is necessary to keep the overall supporting element as small as possible in the minimum lifted position. The outer rod of the telescopic rod is axially guided in the anchoring element and can thus be moved to the lower end of the supporting leg and telescoped into the latter. In the maximum lifted position the extending movement of the telescopic rod is limited by corbresponding stops of the rod and the anchoring element.
To allow the reaching of the minimum lifted position to be electrically indicated, too, the supporting element is provided, according to a preferred aspect of the invention, with a second limit switch and a second actuating element. This actuating element, too, is supported at the supporting member such that it is movable between a first and a second position. Said second actuating element, like the first actuating element, is biased by a biasing force into the first position. When the minimum lifted position has been reached, the supporting member supporting the second actuating element is positioned near the anchoring element stationarily arranged at the supporting leg. The second actuating element axially protruding from the supporting member towards the anchoring element contacts the anchoring element and is, upon further inward movement of the double-spindle arrangement, moved upwards out of the supporting member. This movement out of the supporting member can be detected by the second limit switch such that an electrical indication can show that the minimum lifted position has been reached.
Said second actuating element can further be used to actuate a third limit switch whose switching state indicates that the minimum retracted position, i. e. the extended position of the swivelling rollers, has been reached. When the double-spindle arrangement is moved further into the supporting leg after the minimum lifted position has been reached the second actuating element moves further upwards beyond the supporting member. Above the second limit switch the third limit switch is located which is tripped when the second actuating element protrudes by a certain extent beyond the supporting member, thus indicating the minimum retracted position of the double-spindle arrangement in the supporting leg. Thus this position would be electrically detectable, too. With the aid of all signals of the limit switches a forced cutoff of the driving motor can be controlled, which enhances the operating convenience of the supporting leg.
Alternatively to the employment of the second actuating element for the purpose of actuating the third limit switch it is, of course, also possible to movably arrange a third actuating element on the supporting member, said third actuating element tripping the third limit switch.
When the length-adjustable supporting element according to the invention is used for the supporting legs of a height-adjustable bed, it is sometimes desirable that these beds are moved into a Trendelenburg""s or anti-Trendelenburg""s position. This requires that the side parts (cheeks) connecting the head and base parts are supported, such that they can pivot about an axis extending transversely to the longitudinal extension of the supporting legs, at an lower frame of the bed encircling the supporting legs. By inquiring about the inclination by means of limit switches, automatic cutoff of the drive can be achieved when the Trendelenburg""s or anti-Trendelenburg""s position has been reached. Appropriately a pivoting element is supported, near the supporting member, about a pivoting axis extending transversely to the longitudinal extension of the supporting leg, wherein said pivoting element comprises another actuating element for actuating either the fourth or the fifth limit switch for the purpose of signalling that the maximum inclination of the bed (Trendelenburg""s or anti-Trendenlenburg""s position) has been reached. The two additional limit switches can be attached in a compact arrangement at a common holder.
The invention is described in detail above with reference to the supporting element. This description of the invention is equally applicable when a plurality of said supporting elements are used as height-adjustable supporting legs of a bed, in particular a sickbed and/or nursing bed.